COTTON GRADING

The textile sector is highly profitable and competitive. Cotton fibre quality must meet minimum standards. To remain competitive in the marketplace, the product quality must be maintained.
Cotton is graded based on a number of different factors.
Cotton fibres are graded primarily based on the following quality criteria:
Typical fibre length
The mean fibre length is calculated after ginning. This distance is expressed in either millimetres (mm) or inches. This is how mean fibre length is categorised.

Span size
Utilizing a computerised fibrograph, the 20% span length and 50% span length are examined. It is a standard measure of cotton fibre length that is recognised globally. It can be measured in inches or millimetres. Span lengths over 2.5% are categorised as follows:

Classification of a span length of 2.5%

Fineness fibre

Weight per unit of fibre length determines fibre fineness. Weight and fibre fineness per unit length are inversely proportional to one another. The basis for categorising the fineness of a fibre is its micronaire (Microgrammes/inch) grading.

Fibre tenacity

Fibre maturity-coefficient
The maturity of the fibre is influenced by cotton development. Compound microscopes are used to determine the maturity of fibre. 100 to 200 fibres are placed on a slide and moistened with an 18% caustic soda solution to calculate the maturity co-efficient. The maturity co-efficient is categorised as follows:

Uniformity Ratio
This trait indicates the consistency of cotton fibre length. The ratio of 2.5% span length to 50% span length, presented as a percentage, is the uniformity ratio of cotton fibre. Following is a classification of uniformity ratio:

 Colour appearance of cotton

Classification of cotton colour is based on the  yellow colour present in cotton. In India according to colour cotton is classified as follows:
• White
• Gray
• Pearly